Any power which controlled the World-Island would control well over 50% of the world's resources. The Heartland's size and central position made it the key to controlling the World-Island.

The vital question was how to secure control for the Heartland. This question may seem pointless, since in 1904 the Russian Empire had ruled most of the area from the Volga to Eastern Siberia for centuries. But throughout the nineteenth century:

The West European powers had combined, usually successfully, in the Great Game to prevent Russian expansion.

The Russian Empire was huge but socially, politically and technologically backward—i.e., inferior in "virility, equipment and organization".

Mackinder held that effective political domination of the Heartland by a single power had been unattainable in the past because:

The Heartland was protected from sea power by ice to the north and mountains and deserts to the south.

Previous land invasions from east to west and vice versa were unsuccessful because lack of efficient transportation made it impossible to assure a continual stream of men and supplies.

He outlined the following ways in which the Heartland might become a springboard for global domination in the twentieth century (Sempa, 2000):

Successful invasion of Russia by a West European nation (most probably Germany). Mackinder believed that the introduction of the railroad had removed the Heartland's invulnerability to land invasion. As Eurasia began to be covered by an extensive network of railroads, there was an excellent chance that a powerful continental nation could extend its political control over the Eastern European gateway to the Eurasian landmass. In Mackinder's words, "Who rules East Europe commands the Heartland."

A Russo-German alliance. Before 1917 both countries were ruled by autocrats (the Tsar and the Kaiser), and both could have been attracted to an alliance against the democratic powers of Western Europe (the US was isolationist regarding European affairs, until it became a participant of World War I in 1917). Germany would have contributed to such an alliance its formidable army and its large and growing sea power.

Conquest of Russia by a Sino-Japanese empire (see below).

The combined empire's large East Asian coastline would also provide the potential for it to become a major sea power. Mackinder's "Who rules East Europe commands the Heartland ..." does not cover this scenario, probably because the previous 2 scenarios were seen as the major risks of the nineteenth century and the early 1900s.

One of Mackinder's personal objectives was to warn Britain that its traditional reliance on sea power would become a weakness as improved land transport opened up the Heartland for invasion and / or industrialisation (Sempa, 2000).

Mackinder identified the geopolitical nightmare that was to haunt the world's two sea powers during the first half of the twentieth century — Great Britain and later on the United States. The nightmare was that if Germany or Russia were allowed to control East Europe then this could lead to the domination of the Eurasian land mass by one of these two powers as a prelude to mastery of the world.

Evidence of Mackinder’s Heartland Theory can be found in the works of geopolitician Dimitri Kitsikis, particularly in his “Intermediate Region” model. There is a significant geographical overlap between the Heartland or “Pivot Area” and the Intermediate Region, with the exception of Germany-Prussia and north-eastern China, which Kitsikis excludes from the Intermediate Region. Mackinder, on the other hand, excludes North Africa, Eastern Europe and the Middle East from the Heartland. The reason for this difference is that Mackinder’s model is primarily geo-strategic, while Kitsikis’s model is geo-civilizational. However, the roles of both the Intermediate Region and the Heartland are regarded by their respective authors as being pivotal in the shaping of world history.

This article's factual accuracy is disputed. Please help to ensure that disputed statements are reliably sourced. See the relevant discussion on the talk page.(July 2008)

Though the theory was first conceived before World War I, developments in that war did not disprove it and perhaps gave it some support:

The war was fought almost entirely on land, although Mackinder had not envisaged the vast systems of trenches in Europe.

The development of mechanized military transport and tanks, both needing petroleum, was unforeseen by Mackinder but fitted easily into the theory, as Russia's major oil reserves were located on the western shore of the Caspian Sea.

The Russian Revolution of 1917 made the Heartland itself a threat to the global balance of power for the first time since the mid-nineteenth century, since the Heartland's new government took industrialisation (including modern transport) very seriously, had an ideology which aspired to world domination, and apparently commanded far greater popular support than the Tsars had ever done.[citation needed]

Germany's control of Eastern Europe was too short-lived to be a real test of the Heartland theory.

The Soviet Union's transport infrastructure was still poor in 1941, so one of Mackinder's preconditions was not fulfilled.

Germany had also invaded a large part of Western Europe, and the need to garrison its conquests limited the resources it could devote to war with the Soviet Union.

The Soviet Union limited the impact of its own territorial losses and Germany's territorial gains by relocating many of its factories east of the Urals. Mackinder had not considered this possibility and it could be regarded as a weakness in his theory.

Mackinder's theory implies that modern land transport makes sea power less important than land power. But sea power played a much larger part in World War II than in World War I:

The Battle of the Atlantic, in which Germany tried to prevent the US from sending supplies to Britain (and Russia from 1941), and later to prevent a build-up of Allied forces in Britain as a prelude to the Allied invasion of Europe.

But in terms of Mackinder's theory (especially as he developed it in the 1920s) World War II was 2 "Outer / Insular Crescent" powers (US and Britain) plus the Heartland versus 1 "Inner / Marginal Crescent" power (Germany) and another Outer Crescent power (Japan). The bloodiest part of the whole war was Germany's invasion of the Soviet Union, which was completely consistent with Mackinder's theory.

The Cold War period (late 1940s to late 1980s) was long enough to present a real test of Mackinder's theory, as the Soviet Union:

controlled Eastern Europe and the Caucasus throughout this period and was therefore in a position to threaten or extend its influence into Western Europe and the oil-rich Middle East.

was apparently at a similar economic and technological level to the major Western powers (principally the US).

As a result the Western powers' main objective during the Cold War was to limit the Soviet Union's expansion and influence by any means which would not lead to a nuclear war. Some Western pundits doubted whether the West could survive in the long term (centuries), and hardly anybody seriously considered attempting to reduce the Soviet Union's territory or influence.

But Mackinder had pointed out that "The actual balance of political power at any given time is… the product, on the one hand, of geographical conditions, both economic and strategic, and, on the other hand, of the relative number, virility, equipment and organization of the competing peoples."

And there was increasing evidence that the Soviet Union lacked "virility, equipment and organization":

Despite alarm in 1957–1960 about the "missile gap", in 1961 the US realised that its nuclear weapons exceeded the Soviet Union's in both number and quality.

By the mid 1970s it became apparent that the Soviet Union's economy was experiencing difficulties. The most visible symptom was that it was actually producing less food than in Tsarist times and had to import grain from the US from the early 1960s onwards.

The Soviet war in Afghanistan showed severe weaknesses in the Soviet army's training, morale and equipment which were symptoms of economic and social decay (Odom 1998).

Arguably, the United States has also been using the Heartland Theory in their guidelines in foreign affairs. The US has military bases all over the world and has kept good allies with Saudi Arabia and Kuwait which keep a United States influence in the Middle East, close to the Pivot Area. Having military presences in Afghanistan, the Iraq War and the NATO expansion in Europe gave the United States even more power in an area that is pivotal to having control of the Heartland.[4]

K.S.Gadzhev, in his book Vvedenie v geopolitiku (Introduction to Geopolitics) raises a series of objections to Mackinder's Heartland to start with that the significance physiography is given there for political strategy is a form of geographical determinism.[5]